The invention generally relates to perforating that is optimized for stress gradients around the wellbore.
For purposes of producing well fluid from a formation, the formation typically is perforated from within a wellbore to enhance fluid communication between the reservoir and the wellbore. In the perforating operation, a perforating gun typically is lowered downhole (on a string, for example) inside the wellbore to the region of the formation to be perforated. The perforating gun typically contains perforating charges (shaped charges, for example) that are arranged in a phasing pattern about the longitudinal axis of the gun and are radially oriented toward the wellbore wall. After the perforating gun is appropriately positioned, the perforating charges are fired to pierce the well casing (if the well is cased) and produce radially extending perforation tunnels into the formation.
The formation is subject to tectonic forces, which produce stress on the formation. The stress has multidirectional components, one of which is a maximum horizontal stress. Quite often, the perforating charges are generally aligned with the direction of maximum horizontal stress for purposes of avoiding sand production and/or preparing the formation for subsequent fracturing operations.